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New Tools Could Help Prevent Incel Terrorism

How police inaction failed to prevent a 2018 massacre.

Key points

  • There is a pressing need to identify lone-wolf terrorists before it is too late.
  • The rising violence of the Incel movement is only beginning to be recognized by law enforcement officials and legislators.
  • Tools such as the TRAP-18 could be extremely valuable in predicting risk of violence

On November 2, 2018, a 40-year-old man later identified as Scott Paul Beierle walked into Tallahassee Hot Yoga, a yoga studio in Tallahassee, Florida. Almost immediately after entering, he shot six people, killing two women, A male customer confronted the shooter with either a broomstick or a vacuum cleaner (witness accounts vary) before being pistol-whipped, allowing other customers to flee to safety. Minutes later, officers arrived and found two women, Maura Binkley, 21, and Dr. Nancy Van Vessem, 61, dead at the scene. They also found Beierle's body; he had apparently shot himself.

A military veteran and former high school, Beierle showed few of the warning signs linked with extremist violence aside from prior charges for battery involving him grabbing a woman's buttocks on two occasions. Investigators later determined that he self-identified with the involuntary celibate (Incel) movement after turning up several YouTube videos he had posted in 2014. These videos also showed him sympathizing with the perpetrator of a 2014 Incel shooting, as well as reflecting his deep-rooted misogyny as well as ranting about interracial relationships, illegal aliens, and African-Americans. The International Centre for Counter-Terrorism later classified the Tallahassee shooting as a case of misogynistic terrorism.

While the early Incel movement was originally considered largely harmless and made up of "unlucky in love" individuals forming a loosely-knit community, this changed drastically in 2014 with a mass shooting in Isla Vista, California, in which six people were killed. Though the shooter, Elliot Rodger, killed himself at the scene, his online manifesto clearly described his misogynistic beliefs and made him a hero in violent Incel circles. Since the Isla Vista attack, there have been 13 recorded incidents of violent Incel extremism—a 500 percent increase from 2014 to the present day. As a result, the Southern Poverty Law Center now includes "male supremacy" as an extremist ideology along with religious and racial extremism.

Research looking at the recent rise in Incel violent extremism suggests that it is primarily motivated by three main factors: misogyny, entitlement, and jealousy. Online forums among Incels frequently include all three of these features, along with the jealousy aimed at "Chads" (attractive men) and the sense of unfairness at being ignored by "Staceys" (attractive women") as well as praise for perpetrators of Incel violence such as Rodger and Bierle. Though only a minority of Incel supporters will ever engage in violence, predicting who among them are likely to become "lone wolf" terrorists remains a serious challenge.

A new research study published in the Journal of Threat Assessment and Management analyzes the Tallahassee shooting using a specialized predictive tool intended to identify "lone wolf" terrorists. Christopher J. Collins and James J. Clark of the College of Social Work at Florida State University use a tool known as the Terrorist Radicalization Assessment Profile (TRAP-18), which is itself based on the extensive work of Dr. Reid Meloy and his colleagues in the investigation of lone-wolf terrorism.

The TRAP-18 is made up of two sets of indicators: the first consists of eight warning behaviors that suggest an attack is imminent (proximal risk factors) and 10 predisposing characteristics that make people vulnerable to extremist influences (proximal risk factors). These warning signs are:

  • Pathway warning behavior such as signs of researching, planning, or preparing for an attack. People planning attacks are often caught at this stage through their attempts at acquiring explosives, seeking information on how to construct a bomb, etc. Setting up a workshop in which explosives can be constructed can also be a pathway behavior.
  • Fixation warning behavior indicates an increasingly pathological preoccupation with a specific cause or target of violence. This is usually accompanied by a deteriorating social life or thein ability to hold down a job due to obsessive behavior or thinking.
  • Identification warning behavior involves signs that someone is identifying with other lone-wolf terrorists or showing a desire to be a pseudocommando. They may also show signs of a "warrior mentality," collect guns or military equipment, or proclaim themselves to be an agent of an extremist group. Though many people may express support for groups such as this, making the transition to being a self-proclaimed "soldier" for a specific cause should be viewed with particular concern.
  • Novel aggression is violence that seems to be occurring for the first time and appears out of character. In many cases, this may represent someone testing their limits regarding how much violence they feel capable of inflicting.
  • Energy-burst warning behavior involves a sharp increase in activities relating to their target. Even if this increased activity seems innocent, it can suggest a "ramping up" of whatever is being planned. This can also be associated with a sharp drop in regular activities such as spending time on social media. Some lone wolves may even go "dark" by starting to use encryption to conceal what they are doing online or otherwise hide their activities from friends or family.
  • Leakage involves relaying information to a third party, whether family, a friend, or a news media outlet, about imminent harm being planned against a target. This leakage is usually done as covertly as possible such as with delayed videos, etc. This ensures that the lone wolf can't be stopped ahead of time.
  • Last-resort warning usually occurs as a sign of desperation or distress. This warning indicates that something big is about to happen and often occurs as the result of a loss or fear of an impending loss.
  • Directly communicated threats are the most visible warning sign and the only ones that law enforcement agencies can respond to in many cases. This is why threats are taken so seriously: It may be the final stage in a long pattern of escalation.

In examining Bierele's case using the TRAP-18, Collins and Clark studied approximately 70 pages of Bierle's employment records, disciplinary reports from school districts where he worked, and his U.S. Army service record obtained through the Freedom of Information Act. This provided extensive data concerning biographic events in his life, including personal crises, grievances, and the various "triggers" affecting his later actions. They also examined data about Bierle's routine and habits as witnessed by the people around him to discern any patterns of escalating warning behaviors in the days and weeks that preceded his attack.

Though Collins and Clark could not find any explanation for why Bierle targeted a yoga studio, they did note a series of warning signs that became increasingly clear as the attack grew closer. They also found that Beirle started searching for yoga-related Internet content as early as 2016, including specific searches for "Tallahassee hot yoga." This apparently stemmed from a prior online contact he had with a woman in 2013 who mentioned taking classes there, though she terminated all contact as she considered him to be "crazy" and "weird and insulting."

Though these searches stopped later that same year, they resumed in 2018 in the weeks leading up to his attack. His searches included looking for class schedules as well as phoning the clinic directly, though he didn't speak to anyone. This met the criterion for pathway learning behavior which, along with Bierle's already extensive weapons knowledge, indicated an imminent risk of attack.

He also showed extreme fixation due to his preoccupation with women as "immoral." This included writing and recording music with blatantly misogynistic content as well as committing battery on three different women by grabbing their buttocks. He also repeatedly referred to Elliot Rodger in his online videos and sent his sister-in-law cards and letters containing content on gang rape that she found extremely disturbing. Though she reported her brother-in-law to the Federal Bureau of Investigation (FBI), nothing really came of it.

Analysis of Bierle's writing also showed disturbing signs of identification, i.e., seeing himself as an agent to advance the incel cause. He kept referring to his future "success" and showed greater signs that he wanted to become a pseucommando for the movement with which he had aligned himself. In the weeks immediately preceding the attack, he showed a distinct energy burst pattern with cell phone records showing him making repeated drives to Tallahassee as he apparently began rehearsing his attack. He also purchased a yoga mat and ear protection along with scouting out a regional cheerleaders camp which he had apparently considered as an alternate target.

As he planned his attack, Bierle also carefully arranged various documents in the trunk of his car. These included medical, psychiatric, military, and employment records that he wanted to be found afterward to ensure that he was easily identified. He also left behind a "last resort" warning with statements such as "I have a duty, an obligation, a moral obligation to proceed and act as such” which, along with leaving his motel key in his room, showed that he never intended to return to collect his belongings afterward.

While there was nothing in the available data to show other signs such as leakage, directly communicated threat, or novel aggression, his history of criminal violence, including repeated battery charges, certainly suggests that he was an active risk for future violence even before the Tallahassee shootings.

Could what happened on November 2, 2018, have been prevented if police had been more proactive? Though using the TRAP-18 retrospectively certainly flagged Beirle as a potential lone-actor terrorist, there is still much we do not know about the Incel movement and the recent rise in violence. It also demonstrated that, while mental illness has long been viewed as the primary cause of lone attacks, that certainly does not seem to apply to Scott Paul Bierle, something that likely explains why law enforcement agencies failed to take him seriously until too late.

One thing that Bierle's case clearly identifies is that the FBI and other police forces that dealt with him over the years largely failed to prevent him from becoming more radicalized. Despite his repeated arrests and even an FBI investigation, he consistently fell between the cracks without any kind of coordinated response. Also, many states lack the kind of legislation that might protect women from men holding extremist views. For example, Florida, where Bierle lived and carried out his attack, has no hate-crime legislation in place, something that is also true of 10 other U.S. states.

For now, despite the greater scrutiny the Incel movement is getting from law enforcement agencies, there seems little to prevent future violence. While instruments such as the TRAP-18 are certainly valuable, legislators also need to do their part in passing strong legislation to prevent gender-based violence and rein in extremist movements.


Collins, C. J., & Clark, J. J. (2021). Using the TRAP-18 to identify an Incel lone-actor terrorist. Journal of Threat Assessment and Management. Advance online publication.